1. Field of the Invention
The present invention relates to a rotor of a haymaking machine, the rotor comprising a housing driven in rotation during work about a rotation axis directed upwards, and at least one oscillating arm arranged in a plane substantially perpendicular to the rotation axis, said oscillating arm comprising at least two parts, an internal part connected to the housing and an external part carrying work tools, one of the internal and external parts comprising an engaging portion able to engage along a longitudinal axis partially inside an orifice of an engaged portion of the other of the internal and external parts, the engaging portion and the engaged portion each comprising at least one hole oriented perpendicularly to the longitudinal axis and being able to be connected with one another by means of a connecting device, said connecting device comprising at least one threaded element having a geometric axis and provided with a shoulder, said threaded element passing through each hole of the engaging and engaged portions.
2. Discussion of the Background
In the known rotors of this type, the realization of the oscillating arm in at least two parts, namely the internal part and the external part, is justified by the constraints of packaging and by the constraints of repair of the arm in the case of impact during work. For packaging, the rotor is stored for example on a pallet. To minimize the transport costs, it is desirable to reduce the size of the rotor. Thus, the internal part remains connected to the housing, whereas the external part is separated from the internal part. During the windrowing work, the work tools can encounter obstacles such as stones, which generates great mechanical stresses on the arm. In the case of violent impact, the arm is designed so that the external part bends under the force, whilst the internal part remains intact. Thus, it is sufficient for the user of the machine to dismantle the external part from the internal part, and to straighten or replace the external part, to return the machine into a functional state. Such an operation is simple and costs little.
The threaded element, serving to connect the internal and external parts, is for example formed by a screw with a square or hexagonal head, which passes right through the engaging and engaged parts, and cooperates with a nut to form a bolt. This bolt is tightened on the engaged portion so as to ensure the maintaining of the engaging portion inside of the engaged portion during the rotation of the rotor. The bolt is tightened at a torque which must on one hand prevent its unexpected loosening, and on another hand deform the engaged portion along the geometric axis so that it comes to tighten the engaging portion.
On assembly, a large amount of play can exist between the portions, so that the engaging portion can engage easily inside of the engaged portion. In this case, the tightening of the bolt at a torque allowing to prevent its unexpected loosening is not sufficient for the engaged portion to come to tighten the engaging portion. The compensation of the large amount of assembly play requires a greater torque. Now, the majority of the time, the user of the machine uses the standard equipment which is readily available, for example a conventional thin spanner. Such equipment does not allow tightening to be carried out at the required torque with a good degree of precision. An operating play therefore remains between the portions, which brings about a premature wear of the machine. The user may be tempted to eliminate this play by tightening the bolt with much more force, by mounting, for example, an extension on the tightening spanner. Because this way of proceeding does not permit the force to be proportioned, the engaging and engaged portions are greatly deformed, which makes their subsequent dismantling difficult, even impossible.
On the contrary, a smaller assembly play between the portions may be preferred, so that a relatively small tightening torque, able to be carried out by the user, permits the engaged portion to be tightened against the engaging portion. In this case, the torque which is thus realized is less than the torque required to prevent an unexpected loosening of the bolt, which can bring about its loss and the detachment of the external part of the oscillating arm. Thus, the safety of use of the machine is not optimal. In the case where the bolt is tightened to the required torque to prevent the said unexpected loosening, the deformation of the engaging and engaged portions, which results from this tightening, is such that it makes the sliding of the engaging portion inside the engaged portion with a view to dismantling difficult, even impossible. The use of the machine is indeed complicated.